Have you downloaded “The Synthesis Report” yet? You know, the one from the “Climate Change: Global Risks, Challenges, Decisions” (aka, “The Copehagen Meeting”. )
Naturally, I flipped through to read their comparison of observations to temperatures. After all, annual average temperature this century have fallen mostly below the projections from the AR4 (i.e. the most recent projections by the IPCC.)
So, what does the text say?
Figure 3 shows the trend in surface air temperature in recent decades. 2008 was comparatively cooler than the immediately preceding years, primarily because there was a minimum in the cycle of the sun’s magnetic activity (sun spot cycle) and a La Niña event in 2007/2008. Nevertheless, the long-term trend of increasing temperature is clear and the trajectory of atmospheric temperature at the Earth’s surface is proceeding within the range of IPCC projections.
I blinked a bit when I read this discussion of comparisons between “The” (no adjective) IPCC projections and observations. But then I looked at the figure as, lo and behold, it projections are compared to the TAR ( third report ), not the more recent AR4 ( fourth report. )
If you are wondering how the graph might look if we added information from the AR4? I computed the specific projected values for every 5th year beginning in 1990 and added those values using computer graphics equivalent of red crayon,
So, it seems the 11- year smoothed observed temperatures are falling more or less in the center of projects from the TAR. However, they fall consistently below the newer, supposedly “improved” projections published in the more recent AR4.
I guess this clears up some of Rahmstorf’s previous rhetoric. The observations and “the” IPPC projections for surface anomalies more or less agree if we ignore the fact that the IPPC updated their projections in 2007 and compare temperatures to the older projections. Seems to me that if Stefan could add the temperatures from 2007 and 2008 to the graph, he could have taken the liberty to add the projections from the AR4. Maybe he forgot it exists?
There are other oddities in the report. I mean, why show ocean heat content from Dominguez without mentioning the more recent ocean heat data shows a short term flat trend? Everyone participating in blog – climate -wars knows several peer reviewed papers show this recent flattening.
Ocean heat content trends may pick up again soon.
But even though the flat trend is likely temporary, it’s traditional to show up to date information. Scientific credibility suffers when readily available, widely circulated information is left out of ostensibly scientific reports. People tend to notice the omission and sometimes develop the impression that the authors were fishing for papers that favored the position they want to sell and concealed the others in a basket.
Can you smell the rotting fish?
I at least smell the hardening TAR.
The big jump in OHC from 2001 to 2004 raises an alarm for me. There is no corresponding increase in the rate of change of sea level over the same time period. A 7E22 Joule change in OHC should result in a change in sea level of about 8 mm or about 2 mm/year. As far as I can tell, the jump is necessary to reconcile the measurements from ARGO with the older measurements. Unless there was a fortuitous decrease in contribution from melting land based ice over the same period followed by a massive increase in starting in 2004, the data are inconsistent. Either the ARGO measurements are too high or previous measurements are too low or some combination of both. ARGO is new so there could still be teething problems a la satellite MSU temperatures, but the spotty coverage of the older measurements could be a problem as well. Get rid of the jump and the OHC trend drops.
DeWitt– Argo is new. So, there could be problems associated with it. Or, as you suggest, there could be problems with lack of coverage in the old system.
But not when faced with two systems, the scientists should not be picking their favorite without explaining why, and admitting that one might interpret things differently with the newer data.
Hmm, the uncertainty ranges in that graph seem odd, unless they were calculated specifically for the 11 year smoothed mean. Otherwise there would be a tiny uncertainty range back in, say, 1995.
I wonder what a graph using monthly uncertainty ranges for the TAR projections would look like when compared to recent temperature data? (thats not to say that there is any real reason to user the TAR projections instead of the AR4 projections that I have heard of).
Zeke–
The uncertainty ranges in the TAR have always been odd. I suspect the authors didn’t think about what their uncertainty ranges meant to convey. This propagated into the bizarre discussion in the Rahmstorf 2007 paper where Rahmstorf decreed the temperatures were exceeding the TAR.
I sort of wonder too. Unfortunately, I don’t think the TAR runs are readily available.
A common complaint about the IPCC reports themselves is that their “cut off” deadline prevents the most recent research actually getting in-I suspect that is what is going on with the OHC stuff. Of course, their might be a justification for this-the community needs time to read and either accept or reject the results of new studies, but often it leads to misleading impressions about how “up to date” the reports are.
The very fact that the “analysis” relates to the older TAR data and not to the more recent AR4 is enough to put a smell in the air. It is simply breaking the most elementary tenets of the scientific method.
As for the ARGO data, the team in La Jolla who are involved with this program a few months ago published a set of corrections which were discussed by Pielke Sr. The corrections do not detract from the overall message in the data 5 year data set that ocean temperatures at all depths measured by the ARGO system are falling. What makes the ARGO data so compelling is its remarkable spacial distribution.
The explanation at RC is that the TAR was used because of the long time period of evaluation available.
MikeN,
We all know that ‘long period’ would have meant nothing if the TAR results were off but the AR4 results were closer to the mark.
Also, there is some funny business I don’t understand with the TAR projections. The runs start in 1990 but the period from 1990 to 2001 has some real data incorporated into the models so it does not appear to be a true projection during that period.
If they wanted a “long period”, then why didn’t they use the Hansen 1988 scenarios?
Yeah, I know, silly question.
MikeN–
Oh?
Is that the criteria?
So why is Domingues is cited for ocean heat content. That paper compares AR4 model projections to ocean temperatures. The authors stop their comparisons in 2003, but clearly this can have nothing to do with the lack of age on the projections.
The authors in Copenhagen compared data to the AR4 when they wished to. The did not compare to the AR4 for surface temperatures. There is nothing about the age of the AR4 comparisons that should prevent them from a) mentioning that the surface temperature comparison shown was for the older models that predicts less warming than they currently predict or b) superimposing the AR4 trends on that graph to let people see how the are tracked.
Unless the work on this report started way before the AR4 data was available, which would be pretty dumb all things considered.
Here is the RC comment. It appears I have been banned again to add to this.
Response: Because the report cites a published study here: our 2007 Science paper, where we were looking at how the TAR projections (starting in 1990) compared to observations. For a meaningful comparison you need enough data, and we thought 16 years was enough. The AR4 projections start in 2000 (see Fig. SPM5 of the AR4). Around the year 2016 it may be worth redoing such a comparison, to see how the more recent projections have held up. -stefan]
The Figure showing observations of CO2 EMISSIONS compared with “the envelope of IPCC projections” (p. 11, upper right-hand corner) also uses the TAR projections rather than those from AR4 (this must be the case as the projections as well as the observations start in 1990 not 2000: see Rahmstorf’s comment quoted in #15006).
However, the compound growth rates for projected CO2 emissions given for the 2000-2010 decade in the table in the Copenhagen Synthesis Report do not match those given in Appendix 2 of the TAR scientific report (Table II-1-1). For example, the average annual growth rate for the A1B scenario is given in the 2009 Synthesis Report as 2.42%, but the average annual rate of growth implied by the point-to-point figures given for the A!B projection in the TAR Appendix is 3.42% – a total growth of over 40% (from 6.90 to 9.68 PgC/yr).
The Copenhagen report table gives the false impression that observed CO2 emissions have been rising faster than in any of the SRES projections. This arises partly from the plotting of the trajectory for A1B at 1.00% p.a. lower than it should be, and partly because the circles representing observed emissions for 2005, 2006 and 2007 appear from inspection to be misplaced and compressed.
The TAR was published in 2001 and claims to be relative to 1990. The AR4 was published in 2007, and claims to be relative to the average of 1980-1999. The center of that period is 1990.
The fiction of TAR being “since” 1990 applies equally to the AR4.
Yes, stefan refers to “we” who think something. Those are precisely the “we” who I think deserve criticism for this sort of double-think. That “we” give answers like this shows the tortured mental processes.
Ian, I would suspect that CO2 emissions are above projections.
China has 25% of emissions, so 10% growth there is 2.5% of the total.
Getting up date numbers is pretty hard. Almost every site on Google keeps the emissions numbers from 2004, conveniently keeping the US as the largest emitter, and China nowhere close.
Lucia – apparently the OHC is the new temperature measurement. Well that’s what Australian Senator Fielding was told when he questioned why the CO2 was rising yet temperatures were dropping. He was told the ocean heat content was the more important aspect to consider.
I suppose he considered that OHC was falling which is why he will not be voting for the ETS.
janama–
Technically, OHC is a good measure of warming. One difficulty is that the data are not easily available and the IPCC did not publish specific projections of OHC in their reports.
It’s not entirely clear to me that OHC is a “better” measure of warming. Surface temperatures are more directly connected to the radiative losses. So, in some ways, they are more sensitive means of detecting warming first. OHC reflects a larger thermal mass so, this better reflects how much has occurred.
But, there is a problem associated with mixing. If the mixing in the ocean is very slow, OHC may give ambiguous information.
MikeN (Comment#15026)
RJP Jr. links to this at his new blog. It has emission data through 2006.
http://cdiac.ornl.gov/trends/emis/tre_coun.html
Lucia,
The TAR projections (based on CMIP3 model scenarios) start in 1990 and AR4 projections (CMIP5) start in 2000. That’s clear, or should be.
Zeke,
Rahmstorf et al baselined both TAR projections and observations to the smoothed observations as of 1990, which was fixed. So the uncertainty “fans out” from there. I think the uncertainty intervals should be understood as bounding the smoothed projection, and so should be compared to smoothed observations.
I’m not sure that pre-1990 hindcasts corresponding to each post-1990 scenario run were available in TAR (but I admit I haven’t looked at that in any detail). If so, then of course the baseline procedure used in AR4 could not be used for TAR projections.
Deep
The TAR (third report) projectoins were published in 2001. Saying they “project” since 1990, which is not only before publication of the SAR (second report) but dates back to the FAR (first report), both of which had entirely different projections and which were replaced as each report was published is silly.
I think the uncertainty intervals in the TAR are incoherent. The authors didn’t say what they were and so now have the flexibility to claim whatever the wish. In any case, Stefan himself was pretty vocal about worrying the observations were supposedly exceeding the TAR back in 2007. The smoothed data did not stick out back then: only observations did.
That said, prior to your comment, I said the TAR uncertainty intervals clearly don’t include “weather noise”.
What this means, is you are going to have to claim to take out weather noise some how– a feat that is, literally impossible. Howevver, if, as a comprimise, someone wants to compare 11 year smooth data to the projections, as Rahhstorf does, he should show no observational line after 2003. Rahmstorf “data” lines after 2003 are based on guessing the temperatures after 2008.
What’s the point of comparing predictions to guessed data? That comparison doesn’t make sense. (It also didn’t make sense in 2007 when he published his paper decreeing the observations high compared to the data. If you compare the “observation” line in that paper and the current one, you’ll see the smoothed observations after 2002 have moved. Odd thing for observations to do . . . )
I haven’t suggested the baseline procedure for the AR4 be used for the TAR. I’ve suggested that the same “logic” that claims the TAR are ‘projections’ after 1990 can be used to say the AR4 “projections” from the same time period.
Lucia,
What figure from AR4 are you getting these projections from? Why do the AR4 projections in your figure jump up starting in the year 2000?
Boris–
I computed them from the runs at The Climate Explorer. So, those are the same points I have on my various previous graphs of AR4 projection which agree with figure 10.4 in the AR4; it’s just on this graph I only have the points every 5 years. Looks weird, that way, huh?
The appearance of a jump between 1995 and 2000 is that temperatures drop after large volcanic eruptions and then rise. 1995 is well inside the “dip” “predicted” after Pinatubo erupted. On the continuous graph of the AR4 simulations, the connection to Pinatubo is unmistakable.
If the TAR projection were available numerically, I’d make a clearer graph and you’d see how the AR4 projections appear compared to the TAR. But… I haven’t found a source for the TAR projections available to the public. (Other than digitizing the figures in the TAR.) So, I just put the AR4 images every 5 years.
As far as OHC goes, the “it wasn’t available to them” argument may have some extra validity. The paper is question is pretty dang new.
MikeN, #15026. No, the observed emissions are running well below the projections of the A1B marker scenario as published in the SRES (2000) and Appendix II of the scientific report of the TAR (2001). Preliminary estimates of global CO2 emissions up to 2007 are available on the US Energy Information Administration website. The growth rate from 2007 to 2010 is likely to be lower than in the years up to 2007 because of the current global economic downturn.
Re OHC I recall Gavin at RC saying the Argo data was new and unreliable when someone asked about the DiPuccio analysis that was going around. I suspect that may have something to do with not showing the new recent trends in OHC.
Reading the commentary on several blogs about The Synthesis Report I was tempted to recall a line from a film uttered by Jack Nicolson about telling the truth but I just couldn’t handle it. 🙂
AndrewFL– The Levitus paper on OHC are new, but there have been some other floating around showing the recent flattening.
PaulHClark– I actually agree the ARGO data are new, and may be unreliable. But, it exists and some analyses of the ARGO data have been floating around. It’s existence and preliminary results could have been mentioned. The authors chose not to mention it.
Do you mean this:
Col. Nathan R. Jessep: You want answers?
Lt. Daniel Kaffee: I think I’m entitled.
Col. Nathan R. Jessep: You want answers?!
Lt. Daniel Kaffee: I want the truth!
Col. Nathan R. Jessep: You can’t handle the truth!
I suspect the authors of the Copenhagen synthesis have decided the public “Can’t handle the truth” and so have decided to come up with reasons to withhold information that they prefer not to present.
lucia (Comment#15052)
Exactly!
Lucia,
Well, it’s impossible to tell whether or not the points you have plotted match Figure 10.4 because 10.4 has a 400 year scale and is fairly small to boot.
As for 1995 being part of the “dip” after Pinatubo, this makes no sense. First, it’s a little late. Second, it is quite a bit higher than 1990, so it can’t be a part of a dip.
In any case, even if you eliminate 1995 for that reason, there still appears to be a jump. Shouldn’t the IPCC projections be derived from an ensemble mean? And shouldn’t that mean describe a relatively smooth line? From you plots, it looks as if the IPCC projected rapid warming until 2000, then a slower warming after the turn of the century. This makes no sense to me and does not match projections published in the AR4, specifically figure SPM5.
Then there’s the matter of projections from the AR4 jumping up .1 deg over the short term from the TAR. This doesn’t seem plausible considering that the standard deviation for climate sensitivity among models went down from the TAR to the AR4. Coincidentally, the amount your plots appear to be “out of line” is .1 deg.
Boris–
Gavin has also posted his versions of the averages from The Climate Explorer (during the Monckton Kerfuffle). Our figures match.
Jean S is sending me data to recreate the TAR part. So, I’ll get better graphs for you later today superimposing the AR4 big. Maybe it will turn out eyesight is bad when using the “crayon method”.
There is an entry about the OHC spike here:
http://wattsupwiththat.com/2009/06/02/anomalous-spike-in-ocean-heat-content/#more-8132
I would like to note that I mentioned it on May 7th at 12:25AM
http://www.physicsforums.com/showthread.php?t=311982
Correction: My first note was at May6-09, 04:48 AM .
Also see my comment on May7-09, 01:45 AM where i said about Domingues:
“I don’t know why they used the pre 1970 data. The 1 standard deviation band is so wide, that they might as well insert random numbers. I’m also a little concerned that they cut off their graph at 2003 when Leviticus includes data through 2008.”
They don’t appear to match. You get a .3C increase from 1990-2000 while Gavin shows less than .2C.
lucia, you appear to have missed the point. If reported temps are closer to TAR than AR4 then AR4 must be right since it is improved and better than TAR.
Also, I thought that the failure of ocean heat content to exhibit a rising trend was because either (a) the measurements must be wrong or (b) nobody has yet teamed with Prof. Mann to properly select and weight the more cooperative measured elements to determine a Real though not otherwise apparent trend.
I was also under the impression that if we cannot detect a rising trend in ocean heat content that just means that the pipeline is deeper, more secret and bigger than we had feared and therefore denialism and lukewarmism (“luciaism”) are even more immoral that we had supposed.
Somebody needs to publish the actual numbers from the IPCC and other climate models.
It is more than ridiculous that such an important world-wide issue is demonstrated in “crayon”.
Boris–
The numbers shift depending on whether 2000 is the 12 month average ending with jan 2000 or 2000 is the average from jan 2000 to dec 2001 and also whether you baseline to 1990 exactly or to the average from jan 1980-dec 1999 or set to the average for 1990. My increase from 1990 to 2000 is not 0.3, it’s closer to 0.2.
But your “red crayon” for 1990-2000 is clearly greater than .25C on the figure in this post.
Boris– Yeah. I think I read “0.054” for 1990 and put the 1990 data too low. (The 1990 temperature is not “0” relative to the average of 1980-1999.) I’ll replace that when I create the better graph using something other than the “crayon” method. I’ll double check the various relative temperatures too. (It’s a bit of a pain, since the 11 year smooth 1990 temperatures shift everything relative to everything. But it is possible to show the AR4 relative to the FAR.)
So they’re actually admitting that solar cycles and La Nina are strong enough to override the inexorable rise of mighty CO2. Weren’t there any proofreaders to fix this?
Gary,
It seems they did mention “the sun”. Who’d have expected that two years ago?
Ian, regarding growth rates, I get 3.44% as the A1B growth rate, and that is what has happened the last 6 years(8230 vs 8251 projected). China’s 2000-2002 growth rates were only 3% and 5%, but since then it has been 66% in 4 years.
Ian, the growth rate is actually 3.16, scroll down in the TAR appendix. I think we are misunderstanding either the table or the chart. I don’t think it’s possible for the people who wrote the report to put A1F1 as lower than A1F1.
OK, so I’m trying to determine this discrepancy between the chart in the report and the TAR appendix. Namely, CO2 use grows by either 3.16% or 3.44% in A1B and they reported 2.42% per year for 2000-2010.
First of all, the source for the chart appears to be Raupach 2007 in PNAS, and the whole report is available for free.
The ordering of the scenarios is (B2<A1T<B1<A2<A1B<A1F1)
which does not match the carbon emissions.
The emissions scenarios actually start in 1990, but the 20 year rates don’t match up either. They also didn’t use 100 year rates.
I was able to get 2.43 for A1B looking at fossil fuel use, but none of the other scenarios work.
One possibility is that the SRES scenarios have changed. Looking at the breakdowns in TAR, there are changes in subgroups, but the total emissions numbers are the same for 2000.
I don’t think this is likely, as the ordering wouldn’t change.
Maybe global warming potentials are included. This explains the ordering as A1F1 shows an increase in N2O over A1B, however I haven’t gotten the numbers to add up.
MikeN,
The caption to the Figure on p.11 of the Copenhagen Synthesis Report refers to “Observations of anthropogenic CO2 emissions”, but this is clearly an error. Although the vertical scale is not labelled, the observations align fairly closely with those that have been published by the US EIA and CDIAC in GtC. However, these series relate to fossil fuel and cement emissions only and do NOT include emissions from land use change (estimated by the Global Carbon Project (GCP) Team at 1.5 PgC annually.
According to the latest update posted on the website of the GCP (authored inter alia by Mike Raupach and Pep Canadell of CSIRO, two of the three authors of this section of the Copenhagen report), emissions from fossil fuel and cement “increased from 6.2 PgC per year in 1990 to 8.5 PgC in 2007, a 38% increase from the Kyoto reference year 1990.” If emissions from land use changes were to be added in, the total would be literally “off the chart”.
I can’t get the numbers to add up either, and I don’t see the point in checking whether they may relate to some other measure such as fossil fuel usage or global warming potentials: the caption to the figure refers specifically to emissions.
Lucia,
Agreed that it’s a pain. I’m still trying to figure out why the AR4 projections would be so much higher than TAR’s.
Boris–
I’ll get them plotted. I’ll see if I did some weird mis-match on the baselines. (It’s a bit of a pain. The AR4 baseline is well defined. The TAR one… not so much. It’s “relative to 1990”, but doesn’t specify a type of smoothing. So, Rahmstorf picked one. But I need to figure out the relative zeros.)
But the AR4 does have more warming than the TAR both over the first 30 years of this century, and over the recent period. AR4 has a highly non-linear variation during the 90s due to pinatubo.
Ian, the caption is definitely wrong. There is no way that they could put out a chart that had A1F1 higher than A1B through 2010 if it was just CO2 emissions.
Ian, the emissions growth rates are averaged over all models for that scenario. This only makes a big difference for A1B. Prof Raupach gives 3.36 for the marker scenario for A1B.
Last detail I just noticed. We are calculating the growth rates wrong. We were doing annual compound interest rate calculations, but in fact they are compounding continuously.
Thanks MikeN.
Mike Raupach is Co-Chair of the GCP, but I don’t think he is or has been a ‘Prof’.
OK the GCP authors calculated growth rates compounded continuously, and took the average of the models for each of the six ‘scenarios’. But these are in fact six scenario GROUPS, and it doesn’t seem sensible to characterise all of the ‘models’ in the group as relating to the same scenario – e.g., between 1990 and 2010 the projected primary use of oil increases by only 10% for A1B MiniCAM, but more than doubles for A1B ASF (SRES, pps. 406, 386). The caption is misleading in stating that ‘the ENVELOPE of SRES projections are shown for comparison’ when, for example, A1B ASF fossil fuel emissions are projected to exceed 10 GtC in 2010. It is most unlikely that these emissions will reach this level.
In an interview on Radio ABC Australia on 17 February 2009, Chris Field (a member of the GCP team who is now Co-Chair of IPCC Working Group II) said ‘Fossil emissions have proceeded much more rapidly than anticipated in any of the scenarios that were characterised in detail. The consequence of that is that we are basically entering a domain of climate change that has not been explored by the models. We’re on a different trajectory of emissions and therefore an unknown trajectory of warming’ ( http://www.radioaustralia.net.au/connectasia/stories/200902/s2493602.htm). This was highly misleading. The A1B marker scenario HAS been considered in detail – it’s the average of all of the A1B scenarios that hasn’t been.
Dr Raupach said the caption is incomplete.
When I average the A1B scenarios, the number did work out. His logic is that all of the scenarios are considered equally likely. Separated out, 3 of the 28 scenarios are higher than emissions, and 25 are lower.
MikeN,
Pardon me for persisting, but this is important.
The SRES was explicit that “No judgment is offered in this report as to the preference for any of the scenarios and they are not assigned probabilities of occurrence…†(quoted in AR4, Report of WGI, chapter 10, p. 803). There is therefore no warrant for Dr Raupach’s statement that all of the scenarios are equally likely – i.e., have an equal probability of occurrence.
Perhaps he has been misled by the claim in Whetton et al, 2005, ‘Australian climate change projections for impact assessment and policy application: a review’ (CSIRO Marine and Atmospheric Research Paper 001) that the IPCC scenarios had been ‘deliberately constructed to be equally plausible’ (p. 32).
I advised CSIRO’s Kevin Hennessy of this error in March 2006. He replied promptly, with copies to eight of his CSIRO colleagues, agreeing with me and saying that ‘This error will be corrected.’ When the error had remained uncorrected for six months I raised the matter with Dr Roger Jones, then of CSIRO, in a post to economist John Quiggin’s blog (“Drying Out†thread). Jones replied as follows:
‘Your [Castles’] point about the error in our paper made earlier this year was noted. A request was immediately sent by a colleague through to the relevant people to correct and repost the document after you first pointed this out but it was not done (a production task). On the basis of your recent post pointing out that the phrase had still not been corrected (quelle horreur) we have asked that it be followed through. There is no conspiracy – it was a breakdown in process.â€
The faulty statement remains uncorrected after three years. Although Roger Jones, Kevin Hennessy and Penny Whetton are all IPCC Lead Authors, and also co-authors of CSIRO Marine and Atmospheric Research Paper 001, they have apparently been unable to persuade CSIRO to correct the error in the Paper. This may be because the Paper has been cited in AR4.
Professor Field’s claim that “fossil emissions have proceeded much more rapidly than anticipated in ANY of the scenarios that were characterised in detail†(EMPHASIS added) cannot be sustained. The A1 preliminary marker scenario was one of the four that were used in 1998 to solicit comments during the IPCC’s “open process†and as input for climate models. The projected level of fossil emissions in 2010 was 9.7 PgC/yr in the preliminary version and also in the final version published in the SRES (see the A1p and A1B columns in Table II.1.1 of the TAR scientific report and the A1B-AIM scenario in the SRES: p. 381).
With world primary energy growth in 2008 falling to its lowest rate of growth since 2001 and the expectation of a decline in global outlook this year, it is now unlikely that fossil CO2 emissions will reach the projected level of the A1B marker.
The SRES states explicitly that the marker scenarios “have received the closest scrutiny of the entire writing team and via the SRES open process compared to other scenario quantificationsâ€, and that “The marker scenarios are also the SRES scenarios that have been most intensively tested in terms of reproducibility†(SRES, Technical Summary, section 7, p. 31).
Thus there is no basis for the assertion that “we are basically entering a domain of climate change that has not been explored by the models†as a consequence of the trajectory of actual emissions. Far from being “much more rapid than was anticipated in any of the scenarios†the actual trajectory of emissions in the first decade of the 21st century will probably fall somewhat short of the projections in the most widely used and tested of the A1B scenarios.
Ian, I suspect emissions for 2000-2010 will be roughly equal to the A1B marker, but we’ll see. I think maybe China’s growth will continue, as well as India and some other countries, to the point that as long as US and Europe don’t reduce emissions, growth wil be around 3%.
Perhaps you should ask Dr. Raupach about these probabilities. I’m not really following you.
I think I see your point now. I checked again, and they did say equally likely. Here is the relevant paragraph: You can email Dr Raupach to get the full unpublished note.
The observed trajectory of F for 1990-2004 was compared in Figure 1 of R2007 with the average trajectory of F for each of the six SRES scenario families. The observed growth rate r(F) over the period 2000-2005 exceeds the average growth rate in any scenario family for the decade 2000-2010. We took this approach to test how the alternative hypotheses represented by SRES scenario families compare with reality in the decade since their development, focussing only on emissions. Since no individual scenario is more likely than any other (Nakicenovic et al. 2000), comparison of actual emissions with model ensembles in scenario families is the only viable approach.
Here we provide further detail by examining (1) the variability among individual scenario models within each family, and (2) possible uncertainty in the data.